The human heart is divided into four compartments or chambers. The left and right atria are located in the upper portion of the heart and the left and right ventricles are located in the lower portion of the heart. The left and right atria are separated from each other by a muscular wall, the intra-atrial septum, while the ventricles are separated by the intraventricular septum.
Either congenitally or by acquisition, abnormal openings, holes, or shunts can occur between the chambers of the heart or the great vessels, causing blood to flow therethrough. Such deformities are usually congenital and originate during fetal life when the heart forms from a folded tube into a four chambered, two unit system. The deformities result from the incomplete formation of the septum, or muscular wall, between the chambers of the heart and can cause significant problems. Ultimately, the deformities add strain on the heart, which may result in heart failure if they are not corrected.
One such deformity or defect, a patent foramen ovale, is a persistent, one-way, usually flap-like opening in the wall between the right atrium and left atrium of the heart. Since left atrial pressure is normally higher than right atrial pressure, the flap typically stays closed. Under certain conditions, however, right atrial pressure exceeds left atrial pressure, creating the possibility for right to left shunting that can allow blood clots to enter the systemic circulation. This is particularly worrisome to patients who are prone to forming venous thrombus, such as those with deep vein thrombosis or clotting abnormalities.
Nonsurgical (i.e., percutaneous) closure of a patent foramen ovale, as well as similar intracardiac defects such as an atrial septal defect, a ventricular septal defect, and ablation of the left atrial appendage, is possible using a variety of mechanical closure devices that are implanted into the anatomical site requiring treatment.
However, there are potential drawbacks to using a mechanical closure alone for the treatment of intracardiac defect. For example, some mechanical closures are prone to weakening and breakage. In addition, poor tissue ingrowth or improper positioning of the mechanical closure may lead to continued shunting of blood across the defect. Therefore, given the potential disadvantages of mechanical closures, there is a need in the art for correcting intracardiac defects by utilizing alternate methods. For example, tissue welding may be useful in correcting such defects. Tissue welding, a procedure wherein energy is applied to tissues to join them has been used to correct defects in the arteries, veins, bowel and nerves. Therefore, there is a need in the art for devices applying this technology to correct intracardiac defects.